Systems that use a spatial light modulator to modulate a spatial distribution of a phase, an amplitude, an intensity, and the like of a light are conventionally known. Intensity modulation systems that modulate a light intensity by combining a liquid-crystal element and a polarizer are also known (for example, see patent literature 1). According to these intensity modulation systems, the light intensity is controlled by using the liquid-crystal element to control a polarization state of a light output through the polarizer.